1. Field of the Invention
The invention relates to an engine rotational speed control apparatus that corrects an engine torque through feedback such that an engine rotational speed during idle operation becomes close to a target rotational speed.
2. Description of Related Art
An apparatus described in Japanese Patent Application Publication No. 2003-214231 (JP-2003-214231 A) is known as a control apparatus as mentioned above. In the apparatus described in the publication, a required torque that is calculated in accordance with an operation state of an engine is corrected through feedback in accordance with a deviation of an engine rotational speed from a target rotational speed. Thus, feedback control of the engine rotational speed during idle operation, so-called idle speed control (ISC) feedback is executed. Besides, when a compressor that compresses a cooling medium for air conditioning is in operation, a torque corresponding to a driving load of the compressor (hereinafter referred to as an AC load torque) is obtained to further correct the required torque of the engine, thereby suppressing fluctuations in the engine rotational speed.